yet another DC Controls question

[GregD]

Just a quick question I'm hoping someone can answer. I completed the wiring of the electric fan and DC Controls unit. However, I did not use the yellow wire at all thinking that it was only needed if I wanted the fan to shut off immediately when the ignition is turned off. My thinking was that without the yellow wire, my fan would continue to run after the ignition was off until the coolant temp reached the set point.



However, after reading through the instructions more closely, it looks as though the yellow wire should be wired to a constant 12v source if you want the fan to continue to run after the ignition is off. My question is, is this really necessary? my fan seems to work fine without the yellow wire. It continues to run after the ignition is off and will eventually shut off once it reaches the setpoint. Should I wire the yellow to a constant 12v source or leave it alone?
Thanks,
Greg